Male mice treated with cadmium chloride were mated with normal female mice in order to study the changes of pregnancy rate, average litter size and sex ratio of progenies. The specific activity of the LDH and LDH-x enzymes in nature sperm extracts of the cadmium-treated mice were also detected and compared. In addition, the changes of proteins in the sperm of the treated male mice were analyzed by using the two-dimensional electrophoresis technique. The results demonstrated that there was no significant difference in pregnancy rate, average litter size and sex ratio between experimental and control groups. The specific activity of LDH enzyme in nature sperms of cadmium-treated mice was the same as in the control. However, cadmium could inhibit the activity of LDH -x remarkably. The electrophoretograms have showed, that after the treatment with cadmium, three groups of protein in the extracts of mice sperms either disappeared or changed remarkably